Optimization of sodium storage performance by structure engineering in nickel-cobalt-sulfide.

The development of high-performance electrode materials is crucial for the advancement of sodium ion batteries (SIBs), and NiCo2S4 has been identified as a promising anode material due to its high theoretical capacity and abundant redox centers. However, its practical application in SIBs is hampered by issues such as severe volume variations and poor cycle stability. Herein, the Mn-doped NiCo2S4@GNs composite electrodes with hollow nanocages were designed using a structure engineering method to relieve the volume expansion and improve the transport kinetics and conductivity of the NiCo2S4 electrode during cycling. Physical characterization and electrochemical tests, combined with Density functional theory (DFT) calculations indicate that the resulting 3% Mn-NCS@GNs electrode demonstrates excellent electrochemical performance (352.9 mA h g-1 (200 mA g-1) after 200 cycles, and 315.3 mA h g-1 (5000 mA g-1)). This work provides a promising strategy for enhancing the sodium storage performance of metal sulfide electrodes.